It has long been a problem that, during construction or repair of a bridge, pedestrian access has been restricted or eliminated because such work frequently requires that walkways be torn up, or used as staging areas for work crews and equipment. These repairs often require that all traffic be diverted from the bridge along alternate routes, sometimes many miles away from the destination. While automobile traffic is inconvenienced by these detours, pedestrians and bicyclists can be effectively cut off from their destinations by closure of a bridge because of the distances involved, or because of other obstacles such a road conditions, lack of walkways or paths, or the like. In addition, bridges have been built without pedestrian walkways, forcing pedestrians and bicycles to share the roadway with vehicular traffic, or to take another route.
As a result, it has long been desired to provide a means for permitting pedestrian and bicycle traffic to pass over a bridge while construction is underway and to provide means to retrofit existing structures with pedestrian walkways. At the same time, such means must not interfere with the construction or repair that is underway or with vehicular traffic. Likewise, if the costs of providing such means is too great, already constrained repair budgets will not permit the installation of such means in many, if not most, repair and construction projects. The means so provided must also provide a safe location for pedestrian and bicycle traffic to pass while construction and repair is occurring.